Protective headgear comprising temperature control apparatus

ABSTRACT

A protective headgear, such as a hard hat, is provided that comprises a protective outer shell, which surrounds the head of a wearer and in so doing defines a space between the head of the wearer and the underside of the outer shell; a heat-absorbing member; and a forced air ventilation apparatus. In use, the heat-absorbing member is positioned within the outer shell in the space formed between the head of the wearer and the outer shell, so that the forced air ventilation apparatus can provide a flow of ambient air from outside of the outer shell over the heat-absorbing pad within the space between the head of the wearer and the underside of the outer shell, thereby creating a cooling circulation of air around the head and face of the wearer. Suitably, the heat-absorbing pad comprises a phase-change material (PCM). The headgear may also comprise temperature sensors and systems for monitoring the temperature of the wearer remotely.

FIELD

The present invention relates to ventilated personal protection systems,in particular protective headgear incorporating a cooling means.

BACKGROUND

Personal protection systems in the form of hard hats are typically wornby those in environments or situations where they are at an increasedrisk of trauma to the head. Their main function is to protect the headof the wearer from injury due to flying or falling objects, impact withother objects and electric shock, and preventing force from beingtransmitted down the spine if an impact occurs from above.

Hard hats are required to have acceptable weight, a comfortable fit, andadequate ventilation, while meeting National and International standardsfor impact protection, such as the American National Standards ANSI/ISEAZ89.1-2009 Type 1, Class G and E. Presently there are two main types ofprotective hard hat in common usage in industry, such as theconstruction industry. The first is known as ANSI Type I or CSA Type 1hard hats. Type I hard hats have a relatively simple designincorporating a hard outer shell and inner suspension attached to theinside of the shell. The outer shell is usually made from hard plasticssuch as high-density polyethylene (HDPE), acrylonitrile butadienestyrene (ABS) or other thermoplastic material and acts to resist anddeflect blows to the head. The inner suspension holds the outer shellaway from the head of the wearer. This allows the force from an externalimpact that would otherwise have been transmitted to the head to bereduced.

The other common type of hard hat is ANSI Type II or CSA Type 2. Type IIhard hats are similar to Type I hard hats but comprise an additionalfoam liner, typically made of expanded polystyrene (EPS) that addsfurther protection against both vertical and lateral impacts. The foamliner typically resides between the outer shell of the hard hat and theinner suspension.

Hard hats are also commonly used in a range of industries includingconstruction, heavy and light industrial, petrochemical, oil and gas,mining, road construction, forestry and the utility industries. Hardhats and helmets are also required in other activities where thereexists an increased risk of head trauma. Examples include: motorcycling,riding sports such as horse riding, cycling; winter and extreme sports;and ball sports such as baseball, cricket and American football.Protective head gear is also commonly used in the military and incertain policing environments.

Users of hard hats typically suffer from the fact that they retain heatin hot climates. In desert or tropical climates it is not unusual fortemperatures in working environments to exceed 40° C. on site. Suchtemperatures can also be reached in confined environments such as deepmines, or within poorly ventilated roofing spaces. Due to the restrictedairflow under the hard hat when in use, heat from the covered headportion of the wearer can be trapped underneath. One of the keymechanisms for controlling thermal-regulation in the human body operatesvia evaporative and radiative heat transfer from the head to thesurrounding environment. However, upon exposure to the sun, the outershell of the hard hat can also absorb and trap thermal energy in closeproximity to the head of the wearer and preventing normal thermalregulation and the loss of heat from the body of the wearer. In very hotclimates, enclosed working conditions, or when the wearer is engaged instrenuous activity, the build-up of heat can be severe and potentiallyhazardous. This can lead to discomfort for the wearer, and at worse moresevere consequences, such as heat stroke, a medical condition resultingfrom an elevation temperature of the brain. Heat stroke if not treatedquickly may result in disorientation, disablement or even death. Evenmild cases of heat stroke can lead to impairment of cognitive functionwhich can be extremely dangerous in high risk work locations, such as onconstruction sites or at oil well drilling heads. Furthermore,discomfort caused by heat build-up in hard hats can lead tonon-compliance with health and safety regulations on the wearing of hardhats with workers removing their protective headgear in areas ofincreased risk of harm from objects falling from above, impact withother objects and electric shock.

Previous attempts have been made to provide a means of cooling to hardhats. It is known, for example, that simply changing the colour of theouter shell of the hard hat from yellow or red to white reduces theabsorbed thermal energy from the sun leading to lower internaltemperature within the hat. Addition of a reflective material on theouter surface of the shell may increase the effect. However, thisapproach does not address the problem of body heat generated by thewearer. Ventilation holes in the outer shell also provide a means bywhich the heated air inside the hard hat may be released. Holes in theouter shell, however, can compromise the structural integrity of theshell, also leaving openings through which dust and debris may ingress.

Active cooling systems for helmets and hard hats have been proposed inthe art. Various designs of hard hat that increase evaporative coolingthrough the incorporation of forced ventilation of the space between theouter shell and the wearer's head by means of a fan have been proposedsee for example WO 2013/175932, US 2014/0143934, JP 2012/180606.

US 2004255364 describes a complex helmet cooling system that relies onthermoelectric cooling via the Peltier effect. Systems based onthermoelectric cooling suffer from using a brittle thermoelectricmaterial, the need for a heat sink, a large demand for power resultingin the need for a heavy duty battery, being heavy, and the need for anumbilical cord between the helmet and the battery which presents ahealth and safety hazard. Incongruous systems also reduce user comfortand encourage removal of headgear.

The use of heat-absorbing materials in hats is also known. Full headcover cooling hats are used for cooling the heads of patients inhospitals. This may be to maintain the brain at a decreased temperature,for example to prevent swelling in infant's brains after ascendants ortrauma at birth, or controlling overall body temperature.

Pads comprising heat-absorbing materials are also commerciallyavailable. These pads are placed directly into the inner suspension oftypical Type I or Type II safety helmets. However, the thickness of thepad directly on top of the head of the user can result in instability ofthe helmet due to the shift in the centre of balance of the helmet.Direct contact of the head on the cooling pad may also lead to localiseddiscomfort by causing formation of localised cold spots on the scalp ofthe wearer. The chilling effect of the pad is localised to below the padresulting in poor distribution of the chilled air leading toover-chilling in certain regions, while others are not chilledsufficiently.

The present invention seeks to address the deficiencies of the prior artsystems, most notably, the invention seeks to address the problem ofoverly bulky or incongruous cooling apparatus for protective headgearthat encourages non-compliance of users due to discomfort.

SUMMARY OF THE INVENTION

The present inventors have provided an integrated protective headgearcooling system, suitable for hard hats, helmets and the like, thateffectively cools and ventilates the area between the shell of theheadgear and the head of the wearer. The apparatus of the presentinvention demonstrates considerable advantage in that it is light anddoes not obstruct the free movement of the wearer, and most importantly,does not sacrifice the protection afforded by the shell to externalforces, such as impact or electric shock.

Accordingly, a first aspect of the invention provides for a protectiveheadgear comprising:

-   -   (i) an outer shell, which surrounds the head of a wearer and in        so doing defines a space between the head of the wearer and the        underside of the outer shell;    -   (ii) a heat-absorbing member; and    -   (iii) a forced air ventilation apparatus;

wherein the heat-absorbing member is positioned within the outer shellin the space formed between the head of the wearer and the outer shell,and wherein the forced air ventilation apparatus is arranged so as toprovide a flow of ambient air from outside of the outer shell over theheat-absorbing pad within the space between the head of the wearer andthe underside of the outer shell.

In an embodiment of the invention the flow of ambient air within theheadgear is continuous.

In a specific embodiment of the invention, the heat-absorbing padcomprises a phase-change material (PCM). Suitably, the phase-changematerial comprises one or more of the group consisting of: an organicphase change material; an inorganic phase change material; and aeutectic phase change material. Optionally, the phase-change materialcomprises a salt hydrate; typically the salt hydrate is selected from:sodium sulfate decahydrate and sodium acetate hydrate.

In a specific embodiment of the invention the heat-absorbing padcomprises a contoured surface. Suitably, the contoured surface comprisesat least one selected from the group consisting of: a groove; a channel;a baffle; an indentation; and an undulation.

In a specific embodiment of the invention the forced air ventilationcomprises a fan. Typically, the forced air ventilation comprises one ormore of the group consisting of: an axial-flow fan; a centrifugal fan; amixed flow fan; and a cross-flow fan. In one embedment of the inventionthe fan is an axial-flow fan. Optionally, the fan is an electrical fanand is powered by a renewable energy source or by a power cell. In aparticular embodiment of the invention, the renewable energy sourcecomprises a solar energy array located on the outer shell. Suitably, thesolar energy array comprises at least one photovoltaic cell.

In embodiments of the invention the outer shell comprises a materialselected from the group consisting of: a polymer; carbon fibre;fibre-glass; fibre-metal; metal; and metal alloy. Suitably, the polymercomprises a hard thermosetting plastic or a hard thermoplastic; the hardthermoplastic may be selected from: a high-density polyethylene (HDPE);and an acrylonitrile butadiene styrene (ABS).

In a specific embodiment of the invention, the heat absorbing pad isreversibly attached to the underside of the outer shell. In a specificembodiment of the invention the headgear further comprises a suspensionsystem to support the outer shell at a distance from the head of thewearer in order to provide the space there-between.

In an embodiment of the invention the head gear further comprises asuspension system to support the outer shell at a distance from the headof the wearer in order to provide the space there-between. Suitably, theheat absorbing pad is comprised within the suspension system.

According to one embodiment of the invention the forced air ventilationapparatus is positioned at the rear of the headgear, optionally at thebase of the rear of the headgear. In yet a further embodiment of theinvention the forced air ventilation apparatus is affixed to the outershell.

In one embodiment of the invention the headgear is a hard hat thatconforms to National and/or International standards for ImpactProtection, suitably American National Standards ANSI/ISEA Z89.1-2009Type 1, Class G and E.

Optionally, the headgear further comprises a temperature sensor. In anembodiment of the invention, the temperature sensor controls theactuation and/or speed of the forced air ventilation apparatus.

In a further embodiment of the invention, the headgear comprises aGlobal Positioning System (GPS) locating transponder, and optionally awireless communications system. Suitably, the wireless communicationssystem is configured so as to communicate local temperature informationto a remotely located server.

A second aspect of the invention provides system for monitoringtemperature status information of an individual, in which thetemperature status information corresponds to the temperature within aprotective headgear as described herein that is worn by the individual,wherein the system comprises:

a temperature sensor located within the headgear;

a wireless communications transmitter located within the headgear and incommunication with the temperature sensor;

a wireless communications receiver located remotely;

and a central server that is in communication with the wirelesscommunications receiver,

wherein, the temperature sensor generates temperature status informationand communicates the information to the wireless communicationstransmitter, which in turn transmits the temperature status informationto the remotely located wireless communications receiver, and thus tothe central server.

DRAWINGS

The invention is illustrated by the following drawings in which:

FIG. 1 shows a cross-sectional side view of one embodiment of aprotective hard hat of the present invention;

FIG. 2 shows a lower plan view of the interior of one embodiment of aprotective hard hat of the present invention;

FIG. 3 shows a rear view of one embodiment of a protective hard hat ofthe present invention;

FIG. 4 shows computer predicted performance of one embodiment of aprotective hard hat according to the present invention (a) shows airvelocity contours under the hard shell; and (b) shows thermal imaging ofa cross-sectional side view between the hard shell and the head of auser;

FIG. 5 shows a schematic view of a thermal test apparatus as describedin Example 1;

FIG. 6 shows predicted thermal imaging temperature contours of oneembodiment of a protective hard hat according to the present inventioncomprising a heat absorbing pad with a planar surface;

FIG. 7 shows predicted temperature contours of one embodiment of aprotective hard hat according to the present invention comprising a heatabsorbing pad with a grooved surface.

DETAILED DESCRIPTION

All references cited herein are incorporated by reference in theirentirety. Unless otherwise defined, all technical and scientific termsused herein have the same meaning as commonly understood by one ofordinary skill in the art to which this invention belongs.

As used herein, the term “comprising” means any of the recited elementsare necessarily included and other elements may optionally be includedas well. “Consisting essentially of” means any recited elements arenecessarily included, elements that would materially affect the basicand novel characteristics of the listed elements are excluded, and otherelements may optionally be included. “Consisting of” means that allelements other than those listed are excluded. Embodiments defined byeach of these terms are within the scope of this invention.

The invention provides for cooled personal protection headgear systems,in particular a protective hard hat or helmet, incorporating apparatusand configured for cooling the head and the face of the user when inuse.

FIGS. 1 to 3 show a cross-sectional side view, a lower plan view and arear view of a protective headgear according to one embodiment of theinvention. In embodiments of the invention, the headgear may be aconstruction industry style hard hat, such as those that conform to anANSI Type I or Type II specification.

As shown in FIG. 1, a hard hat 10 comprises an outer shell 12, a heatabsorbing member such as a heat-absorbing pad 14, and forced airventilation 16. The heat-absorbing pad sits within the outer shell inthe space formed between the wearer's head and the shell 12 when in use.The forced air ventilation 16 provides an active flow of ambient airfrom outside of the outer shell over the heat-absorbing pad 14.

It will be understood that the term “forced air ventilation” as usedherein refers to an active air ventilation system that directscirculation of air from the external environment to the space betweenthe underside of the outer shell 12 and the wearer's head. A forced airventilation system will typically comprise at least one air inlet, withventing provided by the gap around the outer circumference of the hat10. Optionally, venting gaps or outlets can also be provided whereappropriate to assist or direct the air circulation as appropriate.

The outer shell 12 is generally shaped to fit over the head and coversat least a portion of the head, typically at least a substantial portionof the frontal and parietal regions of the skull. Suitably the outershell 12 covers at least the upper portion of the head above the eyesand ears. The outer shell 12 may extend down the sides of the head ofthe wearer and/or down the back of the head of the wearer largely inline with the contours of the head to cover at least the majority of thehead excluding the face. The coverage should be sufficient to provideadequate protection of the head of the wearer from injury due to fallingobjects, impact with other objects and electric shock. Typically, suchcoverage should be compliant with national and international safetystandards, for example for the construction, mining or oil and gasindustries.

The outer shell 12 may be formed of any suitable material capable ofwithstanding or deflecting an impact. Typically, the outer shell 12 maybe formed of a polymeric material, such as a hard plastic; a carbonfibre; a fibre-glass; a fibre-metal; or a metal. Where the outer shellis a hard plastic, this may be a hard thermosetting plastic or a hardthermoplastic. Suitably, hard thermoplastics may be chosen to behigh-density polyethylene (HDPE) or acrylonitrile butadiene styrene(ABS). Fibre-metal relates to the class of materials consisting of alaminate of several thin metal layers bonded with layers of compositematerial. Where the outer shell is formed of metal, any suitable metalor metal alloy may be used. Typically, the metal for use in the outershell 12 may comprise aluminum.

The outer shell 12 may comprise a brim 18 that extends outwardly fromthe centre at the base of the shell 12. The brim 18 may extend aroundthe entire circumference of the outer shell 12, or it may just bepresent along a portion of the circumference. Suitably the brim 18 islocated at the front of the outer shell 12 to provide sun shading to theeyes of the wearer. The brim 18 may offer additional protection fromimpact or shock, it may shoed the users eyes and face from weatherconditions such as the sun and rain. The brim 18 may comprise a meansfor channeling water to a particular area of the outer shell, forexample for channeling rain water to the front of the hat to preventdrainage onto the back and/or neck of the wearer in use.

The outer shell 12 may have appendages (not shown). These appendages maybe fixed to or be an extension of the outer shell or the appendages maybe removable. These appendages may extend downwardly in use from thelower edge of the outer shell 12 so as to cover the exposed skin on theface, head and neck of the wearer when in use. The appendages act toprotect the wearer from adverse weather such as the sun, or rain.

The appendages may include drapes, skirts, visors or other shielding.Suitably the appendages comprise a flexible sheet material. The flexiblesheet material may be made from natural or man-made synthetic fabrics.In embodiments of the invention where the appendage comprises a drape orskirt, suitable fabrics may be manufactured from cotton, nylon orpolyester or a combination of these materials. Suitably the fabrics havea sun protection factor (SPF) of at least 2 according to EN ISO24444:2010. Typically the fabric will have an SPF of at least 5, 10, 15,30 or 50. The appendages may be water-resistant or repellent, orwater-proof.

As shown in FIG. 2, embodiments of the hat 10 of the invention may alsocomprise an assembly that acts as an inner suspension 18. The innersuspension acts to support the outer shell 12 at a distance from thehead of the wearer in order to provide a cushioning gap that can absorbthe forces of a direct impact. The inner suspension 18 may comprise anadjustable headband 20 attached to the outer shell 12 and a series ofstraps 22 that span the headband 20.

The headband 20 may be contiguous, or it may be interrupted or partial.The headband may have a fixed circumference, or it may be adjustable.Adjustment of the circumference of the headband may be by any suitablemeans known in the art, for example, via a mechanical adjuster, plasticsnap fitting, buckle, hook and loop tape, or elasticated means. In oneembodiment, the headband 20 is contiguous with a mechanical adjuster.

The straps 22 may span the headband 20 in any direction. Suitably atleast a first strap 22 spans the headband 20 in an approximatelyperpendicular direction to second strap 22 that spans the headbandthereby preventing the headband slipping down the head of the wearer inuse.

In certain embodiments of the invention, the straps 22 will generallyfollow the contours of the inner surface of the outer shell 12. In anembodiment of the invention there will be a gap, space or void 19provided between the outer shell 12 and the straps 22.

In embodiments of the invention, the outer shell 12 may be fitted with avisor to protect the eyes (not shown), ear defenders for use in loudenvironments (not shown), or a chin strap to secure the hat 10 to thehead of the wearer (not shown).

The heat-absorbing pad 14 may be of any shape and size suitable forpositioning under the outer shell 12 of the hard hat 10 in use. Inembodiments of the invention, the heat-absorbing pad 14 has the form ofa planar slab where the thickness of the pad is less than its width.Typically the heat absorbing pad has a thickness of less than 10 cm. Theheat-absorbing pad 14 may have a thickness of less than 8 cm, 7 cm, 6cm, 5 cm, 4 cm, 3 cm, 2 cm, or 1 cm.

All shapes of the pad 14 are provided. Suitably the pad 14 may begenerally circular, polygonal, square, oblong or rectangular. In someembodiments, the pad may take the shape and dimensions of the outershell 12 under which it is positioned to maximise the surface area ofthe heat-absorbing pad 14 without it protruding from the shell 12. Suchan arrangement would enhance the heat absorption of the pad 14, whileminimising the risk of puncture. Alternatively, in other embodiments,the pad may protrude from the outer shell 12 to maximise heatabsorption.

The heat-absorbing pad 14 may be positioned anywhere in the hat 10.Suitably the pad 14 is positioned towards the top of the hat 10, withinthe apex of the outer shell 12, in use so that the air cooled by the pad14 may fall in the direction of the wearer when in use. In an embodimentof the invention that comprises an inner suspension 18, theheat-absorbing pad may be positioned in the gap or void 19 between theouter shell 12 and the straps 22 of the inner suspension 18. In analternative embodiment of the invention, the heat-absorbing pad may befixed to the outer shell 12 directly. Fixing of the pad to the outershell 12 may be by any means. Suitably the means of fixing isnon-permanent (e.g. a reversible fixing) such that the pad 14 may beeasily removed from the hat 10. In embodiments of the invention,reversible fixing is by way of adhesive, hook and loop tape, press studsor straps.

In an embodiment of the invention, the heat-absorbing pad 14 may beformed into a solid planar block, or it may be formed with surfacemodifications that serve to increase the surface area of the pad, and/orto direct air circulation around the pad 14 when it is installed withinthe outer shell 12. Such modifications may comprise one or more grooves,channels, undulations, baffles and/or indentations. These modificationsmay serve to increase or decrease the velocity of circulating air withinthe void 19 between the outer shell 12 and the straps 22 of the innersuspension 18 and, thereby, alter the cooling characteristics of the hat10.

The heat-absorbing pad 14 may be formed of any material that can absorbheat energy. In an embodiment of the invention, the pad 14 may be formedof heat conductive materials such as metal, with or without the use of aheat-sink arrangement, or the pad may be formed of materials with a highthermal capacity such as a ceramic, stone or concrete that may bechilled prior to use. Typically, the material of the heat-absorbing padmay be a phase-change material.

A phase change material (PCM) is generally a substance with a highlatent heat capacity. Latent heat is the energy required to convert asolid into a liquid, or a liquid into a vapour without a change in itstemperature. PCMs latent heat storage can be achieved throughsolid-solid, solid-liquid, solid-gas and liquid-gas phase changes. Wateris an example of a phase change material. The known method ofevaporative cooling works on the principle of cooling air by passing itover a wet surface where it is cooled through the absorption of the heatenergy in the air by the water thereby providing the required latentheat of vaporisation to evaporate the liquid water to gaseous watervapour. Hence, in one embodiment of the invention the heat-absorbing pad14 may comprise a water impregnated material, such as a dampened sponge,fabric pad, wicking material or an equivalent matrix. More typically,commercial heat-absorbing materials for PCMs rely on the solid-liquidphase change. Commercial PCMs may be formed of a wide-range ofmaterials, classified into three main groups: organic PCMs are based onorganic materials, i.e. comprised primarily of carbon and hydrogen, suchas paraffin, sugar alcohols or fatty acids; inorganic PCMs are based oninorganic salt hydrates, such as sodium acetate hydrate or sodiumsulfate decahydrate; and eutectic PCMs, generally based on salt-watersolutions.

All forms of PCM are suitable for use in the heat absorbing pad 14 ofembodiments of the invention herein described. Suitably, the PCM for theinvention herein described uses a PCM that relies on the solid-liquidphase change. Typically the PCM may be selected from commerciallyavailable PCMs, such as those listed in Table 1 below.

TABLE 1 PCM Materials Melting Temp Heat of fusion Density Material ° C.kJ/kg kg/m3 Sodium sulfate decahydrate 32.4 252 1460 (Na₂SO₄•10H₂O)PureTemp ™ 29 (PureTemp) 29 189 850 Climsel ™ C28 (Climator) 28 162 1380Climsel ™ C32 (Climator) 32 162 1420 Paraffin 18-Carbons 28 244 777Paraffin 19-Carbons 32 222 786

The use of a PCM as the material from which the heat-absorbing pad 14 isformed has a number of advantages. Firstly, PCMs have a high capacityfor heat absorption. In addition, the heat absorption capacity of thePCM is regenerative, for example by cooling the material viarefrigeration; therefore the material may be used repeatedly withoutloss of function. Furthermore, as pads comprising PCMs generally are notchilled below their freezing point, therefore there is minimal risk ofinjury (through frost bite) or discomfort from over-cooling a heatabsorbing pad 14 comprising a PCM.

The PCM may be chosen to have a phase change temperature suitable forthe environmental conditions and body temperature of the user. Examplesof suitable PCM comprising pads may include, for example, salt hydratebased PCMs including the commercially available Climsel™ C28 (ClimatorSweden AB, Skövde, Sweden). The high heat storage capacity in the phasechange from solid to liquid and the advantageous phase changetemperature of 32° C. makes this material particularly appropriate to beused in this application. The PCM may also be chosen to be non-toxic incase of the risk of leakage of the material from the pad 14.

FIG. 3 shows a rear view of a hat 10 according to an embodiment of theinvention where the air inlet is positioned at the rear of the hat 10.In this embodiment of the invention, the hat 10 comprises a ventilationaperture 16. The aperture 16 allows a flow of ambient air from outsideof the outer shell 12 to enter the void 19 between the wearer's head andthe underside of the outer shell 12. In a specific embodiment of theinvention, the aperture 16 comprises forced air ventilation apparatus 17which directs airflow into the void 19 and across the surface of theheat-absorbing pad 14. The pad 14 not only acts to cool the air passingover it but also to distribute the cooled air surrounding theheat-absorbing pad 14 around the interior of the outer shell 12.

The forced air ventilation apparatus 17 may be positioned anywhere onthe hard hat 10 provided the airflow is directed under the outer shell12 and across the heat-absorbing pad 14. Suitably the at least oneaperture 16 is positioned within the outer shell 12, although inembodiments of the invention a plurality of apertures may be present.Typically the forced air ventilation apparatus 17 is integral with theouter shell 12 and in close proximity to the aperture 16. Suitably, theforced air ventilation apparatus 17 may be positioned on the hat 10above the face of the wearer when in use, or alternatively, it maysuitably be positioned on the opposite side of the hat 10 above the napeof the neck of the wearer when in use. In embodiments of the invention,the forced air ventilation apparatus 17 may be positioned on the hat 10at the base of the outer shell 12 directing a flow of ambient airupwardly into the void 19, past the heat-absorbing pad 14. Suitably, theheat-absorbing pad 14 will be positioned in the void 19 such that theairflow is directed into contact with the heat-absorbing pad 14. Airflowpast the heat-absorbing pad 14 may be in any form. In embodiments of theinvention, airflow may be directed above, below and/or to the side ofthe heat-absorbing pad 14, suitably, the airflow is directed above andbelow the heat absorbing pad 14.

In embodiments of the invention, where the aperture 16, and optionallythe forced air apparatus 17, is positioned on the rear of the hat 10,diametrically opposed to the face of the wearer when in use, airflow ofambient temperature is directed into the void 19 under the outer shell12, past the heat-absorbing pad 14, with the then cooled air venting thehat 10 above the face of the wearer in a downward direction. In thisway, the wearer is exposed to a constant stream of cooled air passingover the face thereby facilitating effective radiative and evaporativecooling of the wearer's head and upper body.

Alternatively, in embodiments of the invention when the forced airventilation 17 is positioned on the front of the hat 10, above the faceof the wearer when in use and with or without an aperture 16, airflow isdirected under the outer shell 12 into the void 19, across the surfaceof the heat-absorbing pad 14, with the cooled air then exiting the outershell 12 of the hat 10 above the neck of the wearer in a downwarddirection. In this way, the wearer is exposed to a constant stream ofcooled air passing over the neck.

According to the present invention, the combination of the forced airventilation and the heat-absorbing pad 14 in a hard hat 10 provides anumber of advantages.

Firstly, the cooling effect of the heat-absorbing pad 14 is no longerlocalised to one specific head area of the wearer within the outer shell12 of the hat. In addition, the effect of ventilation and air coolingmay be extended to also cover the face, neck and upper body.

In addition, the airflow past the heat-absorbing pad 14 acts todistribute the cooled air throughout the interior of the outer shell 11,thereby preventing uncomfortable over-cooling of the part of the headclosest to the heat-absorbing pad, and insufficient cooling in parts ofthe hat 10 more distant from the heat-absorbing pad 14. Furthermore,airflow through the void 19 between the head of the wearer and the outershell 12 prevents local heating of the air trapped in this region due tothe direct heating effects of the sun on the outer shell 12 or fromradiative and evaporative thermal transfer from wearer's body. Suchheating may otherwise lead to premature exhaustion of the cooling effectof the pad 14.

The forced air ventilation apparatus 17 may comprise any type ofmechanical or forced ventilation device, or mixed mode or hybridventilation that uses both mechanical and natural ventilation that issuitable for generating air circulation. In an embodiment of theinvention, the forced air ventilation apparatus 17 comprises an electricfan assembly. The electric fan assembly may be of axial-flow,centrifugal, mixed flow or cross-flow design. In an embodiment of theinvention, the fan is an axial-flow electric fan.

The forced air ventilation apparatus 17 may be powered by any suitablemeans. In embodiments of the invention, the forced air ventilationapparatus 17 may be powered by renewable energy sources, such as solarenergy; or by other electrical power sources such as non-rechargeable orrechargeable power cells (e.g. batteries); or by mains electricity.

Suitable sources of renewable energy in the context herein are thosethat can provide sufficient electrical power to the forced airventilation apparatus 17 so that it may provide a sufficient airflow toachieve the benefits of the invention. Suitably the collection means maybe sized to be self-contained on the hat 10. In embodiments of theinvention wherein the forced air ventilation apparatus 17 is powered bysolar energy, a solar generating array or panel (e.g. a photovoltaicsolar cell) may be advantageously positioned on the outer surface of theof the outer shell 12 to maximise its exposure to the sun, however, thepositioning of the solar panel may be at any suitable position on thehard hat 10 to provide sufficient power output to supply the forced airventilation apparatus 17.

In embodiments of the invention where batteries are used, the batteriesmay be non-rechargeable, for example, alkaline batteries, mercurybatteries, silver-oxide batteries and zinc-carbon batteries.Alternatively, the batteries may be rechargeable, for example,nickel-cadmium batteries, nickel metal hydride batteries, lithium ion orlithium polymer batteries, or lead acid batteries.

In embodiments where the fan is powered by renewable energy sources,batteries may also be employed to temporarily store the power generatedfrom the renewable source. This is particularly advantageous when thesun is obscured by cloud, when the user is not located in directsunlight or at dusk or night time. The stored power may then be used topower the forced air ventilation apparatus 17 when the power generatedfrom the renewable source is insufficient to maintain a satisfactoryairflow. The battery employed for storing the energy from the renewablesource may be rechargeable and, for example, selected fromnickel-cadmium batteries, nickel metal hydride batteries, lithium ion orlithium polymer batteries, or lead acid batteries.

In embodiments of the invention requiring a local power source, such asbatteries, these may be positioned at any suitable position on the hat10, or elsewhere on the wearer within a power pack that may be linked tothe hat 10 via an electrical connection such as a wire. The choice ofpositioning of the power pack depends on the balance of benefits ofreducing weight of the hat by placing the power pack on the body of thewearer, compared to the freedom of movement obtained by having the powersource positioned on the hat 10 thereby eliminating the need for a wiredconnection out from the hat 10 that may be subject to snagging orotherwise impair the movement of the wearer. Suitably the local powersource is positioned on the hat 10, typically approximatelydiametrically opposed to the forced air ventilation apparatus 17 tobalance the weight distribution of the hat as much as possible.

The airflow of the forced air ventilation apparatus 17 is controlled toa value typically less than 1 m³/min. In embodiments of the invention,the airflow of the fan may be less than 0.9 m³/min, 0.8 m³/min, 0.7m³/min, 0.6 m³/min, 0.5 m³/min, 0.4 m³/min, 0.3 m³/min, or 0.2 m³/min.Suitably, the airflow is more than 0.01 m³/min. typically the airflow ismore than 0.05 m³/min or 0.1 m³/min. Suitably, the airflow is more than0.01 m³/min. The data shown in the non-limiting examples provided hereinare for an average volume flow rate of typically 0.35 m³/min.

FIG. 4 shows the predicted air velocity contours in a hard hat accordingto an embodiment of the invention. In the embodiment shown, theheat-absorbing pad 14 is positioned between the outer shell 12 and thewearer's head 20. The forced air ventilation apparatus 17 is positionedat the rear of the hat 10. The modeled airflow is discussed in detailbelow in Example 2.

As shown, ambient air enters the void 19 between the outer shell 12 andthe wearer's hat under the influence of the forced air ventilationapparatus 17. The air then passes across the heat-absorbing pad 14before exiting at the front of the outer shell 12 and flowing over theface of the user. Due to the symmetry of the design, a forced airventilation apparatus 17 positioned at the front of the hat 10 would beexpected to provide a similar airflow with cooled air exiting the outershell 12 at the rear and continuing to flow down over the neck of thewearer.

In embodiments of the invention where the heat-absorbing pad is grooved,contoured or has undulations, they may be formed, or oriented so thatthey provide channels or passageways for the air to pass theheat-absorbing pad in the direction from the forced air ventilation tothe exit vent of the helmet. The grooves or undulations formed in theheat-absorbing pad may be used to direct airflow in a direction that isbeneficial to distribution of the cooled air around the interior of thehat 10—e.g. to a particular vent location. Alternatively, grooves orundulations may be used to create turbulent airflow in order to disruptconvection currents within the void 19 and enhance the cooling effect.

In an embodiment of the invention, the hat 10 may further comprise asensor to monitor the either the void 19 temperature and/or the skinsurface temperature of the wearer. The sensor may be of any formsuitable for measuring thermal energy. Suitably the temperature sensormay comprise: an infra-red temperature sensor, or a thermocouple.

In an embodiment of the invention, the temperature sensor communicatesdiscrete temperature information of the wearer to a central server viawireless or mobile telecommunications system. The central server may belocated within the site management facility, for example on aconstruction site, thereby alerting site management to the existence ofpotentially dangerous working conditions. In an alternative embodimentof the invention the sensor may comprise a close range wirelesscommunication transponder (such as an NFC or Bluetooth® device) allowingthe transmission of temperature information to the wearer themselves. Inone embodiment, the wearer can be alerted to potentially harmfultemperature conditions via wireless communication with an application(an ‘app’) held on their mobile telecommunications device. Hence, if theskin or void 19 temperature increases above a given threshold it mayindicate that that the heat-absorbing pad 14 in the hat 10 is no longerproviding sufficient cooling of the wearer and the pad 14 needs to bereplaced or recharged. Alternatively, it may indicate that theenvironment that the wearer is exposed to is beyond the safe operatingparameters for the cooling effect of the hat 10 to maintain the wearer'stemperature at a safe working level. Monitoring of the wearer'stemperature in this way is therefore an effective way of monitoring safeworking conditions for the wearer, and may provide an effective loggingmethod as evidence of safe working and compliance with local labourregulatory laws.

The temperature sensor may be used for thermostatic control of theforced air ventilation apparatus 17. In environments where the need forcooling may be variable, such as when the wearer is moving from insideto outside, or from a hot environment to a less hot environment, or isengaged in work that is more or less strenuous, it may be desirable tovary the speed of the airflow generated by the forced air ventilationapparatus 17 to match the present need. In embodiments of the invention,the speed control of the forced air ventilation apparatus 17 may beachieved by any suitable means such as by manual control by theoperation of a speed controller by the wearer, or it may be automatic,using the temperature sensor in a feedback arrangement operating theforced air ventilation apparatus 17 only once a certain temperaturethreshold is exceeded. In embodiments of the invention, the speed of theforced air ventilation apparatus 17 may increase with the reportedtemperature through a range until the maximum speed of the forced airventilation apparatus 17 is reached.

In an embodiment of the invention, the hat 10 may further comprise a GPStracking device, or other means for monitoring the geographical positionof a worker. The linking of temperature information with geographicallocation and time data may offer a means of identifying particularlydifficult working areas to which workers have been exposed. It may alsoprovide an effective means of logging exposure to conditions acrossworking zones at a local or even global level. Hence, the inventionprovides a system for monitoring an important aspect of safe workingconditions for workers across the world.

GPS tracking functionality within the hat 10 may also provide effectiveidentification, via geo-tagging, of the location of the wearer in theevent of an accident or other emergency.

The invention is further exemplified in the following non-limitingexamples.

EXAMPLES Example 1 Effect on Temperature

An embodiment of the hard hat 10 according to the present invention wassubjected to a simulated environment typically found in a hot climate ofincreased ambient air temperature and/or direct irradiated heat.

The test used a hard hat 10 according to the invention comprising anouter shell 18, a heat-absorbing pad 14, inner suspension 18, and forcedair ventilation apparatus 17 mounted at the front of the hat 10, poweredby batteries in a battery pack 23 mounted at the rear of the hat 10.Comparative example hard hats that do not comprise a heat-absorbing pad14 and/or forced air ventilation apparatus 17 were simulated by removingthe heat-absorbing pad 14 from the hat 10 according to the inventionand/or deactivating the forced air ventilation.

As shown in FIG. 5, the test involved placing the hat on a dummy head 24in an insulated enclosure 26. A heater 28 was then used to heat the airinside the enclosure 26 to a set temperature in excess of the ambientair external to the enclosure 26. The heater 28 was controlled by atemperature control unit 30 attached to a thermocouple thermometer 32inside the enclosure 26.

Direct radiant heat from the sun was simulated by a 60 W tungsten lightbulb 34 placed at the top of the enclosure 26 above the hat under test.This bulb 34 and the forced air ventilation apparatus 17 were separatelycontrolled by a switching unit 36 positioned outside of the enclosure.

Heat from the wearers head was simulated by the radiant heat from a 40 Wtungsten light bulb 38 mounted inside the dummy head 24. To mimic aconstant temperature of the head of the wearer unaffected by the ambienttemperature increase, or radiant heat in the test enclosure 24, the bulb38 and an identical bulb 40 were controlled simultaneously via controlunit 42 attached to a thermocouple thermometer located inside anidentical hat 44 in a separate enclosure 46 held at ambient temperature.The hat 44 was also placed on a dummy head 46 within which the bulb 40was mounted.

All temperature measurements were taken from a thermocouple thermometer48 mounted in the hard hat under test once a steady-state temperaturereading had been reached.

The thermal experiment results of the test are provided in Table 2below:

TABLE 2 Thermal experiment results Experiment Conditions Cooling meansT1 T2 Difference (T2 − T1) No. Bulb 34 Bulb 38 PCM pad Fan (° C.) (° C.)(° C.) 1 On Off Not Off 42 42 0 present 2 On On Not Off 42 56 +14present 3 On On Not On 42 48 +6 present 4 Off On Not On 42 46.5 +4.5present 5 Off On Not Off 42 52 +10 present 6 On On Present Off 42 34 −67 On On Present On 42 28 −14

The results clearly show that without any form of cooling, thetemperature within a hard hat increases under simulated hot climateconditions of increased ambient temperature and direct radiated heatfrom the sun (Experiment 2, +14° C. increase).

The increase was lessened through the use of the fan alone (Experiment3, +6° C. increase). The use of the PCM pad alone also provided adecrease (Experiment 6, −6° C. reduction).

The results clearly show, however, that the combination of the presenceof a heat absorbing PCM pad and a forced ventilation means in the formof a fan mounted on the front of the hard hat provides superior coolingof the hard hat. Experiment 7 demonstrated a measured temperaturedecrease of 14° C. in the hat compared to the surrounding airtemperature within the sealed enclosure 24.

Example 2 Temperature and Air Velocity Contour Modeling

FIG. 4 shows the predicted air velocity contours in a hard hat accordingto an embodiment of the invention. The heat-absorbing pad 14 ispositioned between the outer shell 12 and the wearer's head 20. Theforced air ventilation apparatus 17 is positioned at the rear of the hat10.

According to the model, ambient air enters the void 19 between the outershell 12 and the wearer's hat under the influence of the forced airventilation 16. The air then passes either side (top and bottom asshown) of the heat-absorbing pad 14 before exiting at the front of theouter shell 12 and flowing downwards over the plane of the face of theuser. Due to the symmetry of the design, a forced air ventilation 16positioned at the front of the hat 10 would be expected to provide asimilar airflow with cooled air exiting the outer shell 12 at the rearand continuing to flow down over the neck of the wearer.

FIG. 6 shows the predicted temperature contour map of the same model ofa hard hat according to an embodiment of the present invention. The hatshown in FIG. 6 is a cross-sectional view from the side of the hat.

FIG. 7 shows a similar predicted temperature contour map of a hard hataccording to an alternative embodiment of the invention that uses agrooved PCM pad. The hard hat shown in FIG. 7 is a cross-sectional viewfrom the rear of the hat.

The pre-processor GAMBIT was used in meshing the simulated model intomore than 4,000,000 tetrahedral cells. Using growth rate functionoption, meshes could be dense and smaller near air supply slots andhuman bodies; and growing when further away. This number of cells usedwith the growth function technique is considered sufficient, as theinventors performed grid independency check. Commercially availablesimulation software “Fluent 6.3” was incorporated to solve conservationof mass, momentum and energy in the processing of air distribution, andto analyze turbulence affection combined heat transfer on airdistribution. In this work, the so-called standard k-ε turbulence model,one of the most widespread turbulence models for industrialapplications, was utilized. Basic parameters included air temperature,air velocity, relative humidity and turbulence parameters were used fornumerical prediction of indoor air distribution.

The various boundary conditions assumed for all the studied cases hereindescribed later.

-   -   Human Body was set as wall with constant surface temperature of        32° C. which is the skin temperature at this activity level.    -   PCM was set as wall with constant temperature of 28° C. which is        the melting temperature of the chosen material.    -   Helmet inner surface, was set as wall with heat flux of 50 W/m²        which is equivalent to the transferred heat due to incident        solar intensity on the outer side.    -   Electric fan with static pressure of 30 Pa.    -   Ambient Temperature of 37° C.

The lighter areas on both FIGS. 6 and 7 signify cooler temperatures. Ascan be clearly seen in both FIGS. 6 and 7, the pad itself is whiteindicating that it is cold. More importantly, the areas immediatelyadjacent the pad between the outer shell 12 and the head of the wearerare also considerably cooler than the ambient air temperature (shown asdark). It is evident that the cooling is reasonably uniformlydistributed within these areas.

Furthermore, it can be clearly seen on the left hand side of FIG. 6 thatthe air immediately adjacent to the side of the head is lighter incolour signifying that cooled air is present in this region. Dependingon the orientation of the positioning of the fan at the back or front ofthe hat, this area would represent the face or back of the head/neck ofthe wearer. Hence, the apparatus of the present invention advantageouslyprovides effective cooling not just around pad but uniformly over largerregion.

It is therefore demonstrated that the combination of a PCM pad and aforced ventilation in the form of a fan mounted directing airflow acrossthe pad not only provides more uniform distribution of the air cooled bythe pad within the area under the outer shell 12, but also provides apleasant stream of cooled air to the face or back of the head/neck ofthe wearer in use, avoiding uncomfortable cold spots.

The aforementioned embodiments are not intended to be limiting withrespect to the scope of the appended claims, which follow. It iscontemplated by the inventors that various substitutions, alterations,and modifications may be made to the invention without departing fromthe spirit and scope of the invention as defined by the claims.

1. A protective headgear comprising: (i) an outer shell, which surroundsthe head of a wearer and in so doing defines a space between the head ofthe wearer and the underside of the outer shell; (ii) a heat-absorbingmember; and (iii) a forced air ventilation apparatus; wherein theheat-absorbing member is positioned within the outer shell in the spaceformed between the head of the wearer and the outer shell, and whereinthe forced air ventilation apparatus is arranged so as to provide a flowof ambient air from outside of the outer shell over the heat-absorbingpad within the space between the head of the wearer and the underside ofthe outer shell.
 2. The protective headgear of claim 1, wherein the flowof ambient air is continuous.
 3. The protective headgear of claim 1,wherein the heat-absorbing pad comprises a phase-change material (PCM).4. The protective headgear of claim 3, wherein the phase-change materialcomprises one or more of the group consisting of: an organic phasechange material; an inorganic phase change material; and a eutecticphase change material.
 5. The protective headgear of claim 4, whereinthe phase-change material comprises a salt hydrate.
 6. The protectiveheadgear of claim 5, wherein the salt hydrate is selected from: sodiumsulfate decahydrate and sodium acetate hydrate.
 7. The protectiveheadgear of claim 1, wherein the heat-absorbing pad comprises acontoured surface.
 8. The protective headgear of claim 7, wherein thecontoured surface comprises at least one selected from the groupconsisting of: a groove; a channel; a baffle; an indentation; and anundulation.
 9. The protective headgear of claim 1, wherein the forcedair ventilation comprises a fan.
 10. The protective headgear of claim 9,wherein the forced air ventilation comprises one or more of the groupconsisting of: an axial-flow fan; a centrifugal fan; a mixed flow fan;and a cross-flow fan.
 11. The protective headgear of claim 7, whereinthe fan is an axial-flow fan.
 12. The protective headgear of claim 9,wherein the fan is an electrical fan and is powered by a renewableenergy source or by a power cell.
 13. The protective headgear of claim12, wherein the renewable energy source comprises a solar energy arraylocated on the outer shell.
 14. The protective headgear of claim 13,wherein the solar energy array comprises at least one photovoltaic cell.15. The protective headgear of claim 1, wherein the outer shellcomprises a material selected from the group consisting of: a polymer;carbon fibre; fibre-glass; fibre-metal; metal; and metal alloy.
 16. Theprotective headgear of claim 15, wherein when the material is a polymer,the polymer comprises a hard thermosetting plastic or a hardthermoplastic.
 17. The protective headgear of claim 16, wherein, thehard thermoplastic is selected from: a high-density polyethylene (HDPE);and an acrylonitrile butadiene styrene (ABS).
 18. The protectiveheadgear of claim 1, wherein the heat absorbing pad is reversiblyattached to the underside of the outer shell.
 19. The protectiveheadgear of claim 18, wherein the head gear further comprises asuspension system to support the outer shell at a distance from the headof the wearer in order to provide the space there-between.
 20. Theprotective headgear of claim 1, wherein the head gear further comprisesa suspension system to support the outer shell at a distance from thehead of the wearer in order to provide the space there-between.
 21. Theprotective headgear of claim 20, wherein the heat absorbing pad iscomprised within the suspension system.
 22. The protective headgear ofclaim 1, wherein the forced air ventilation apparatus is positioned atthe rear of the headgear.
 23. The protective headgear of claim 22,wherein, the forced air ventilation apparatus is positioned at the baseof the rear of the headgear.
 24. The protective headgear of claim 1,wherein, the forced air ventilation apparatus is affixed to the outershell.
 25. The protective headgear of claim 1, wherein the headgear is ahard hat that conforms to National and/or International standards forImpact Protection.
 26. The protective headgear of claim 25, wherein thehard hat conforms to American National Standards ANSI/ISEA Z89.1-2009Type 1, Class G and E.
 27. The protective headgear of claim 1, whereinthe headgear further comprises a temperature sensor.
 28. The protectiveheadgear of claim 27, wherein the temperature sensor controls theactuation and/or speed of the forced air ventilation apparatus.
 29. Theprotective headgear of claim 1, wherein the headgear further comprises aGlobal Positioning System (GPS) locating transponder.
 30. The protectiveheadgear of claim 1, wherein the headgear further comprises a wirelesscommunications system.
 31. The protective headgear of claim 30, whereinthe wireless communications system is configured so as to communicatelocal temperature information to a remotely located server.
 32. A systemfor monitoring temperature status information of an individual, in whichthe temperature status information corresponds to the temperature withina protective headgear of claim 1 that is worn by the individual, whereinthe system comprises: a temperature sensor located within the headgear;a wireless communications transmitter located within the headgear and incommunication with the temperature sensor; a wireless communicationsreceiver located remotely; and a central server that is in communicationwith the wireless communications receiver, wherein, the temperaturesensor generates temperature status information and communicates theinformation to the wireless communications transmitter, which in turntransmits the temperature status information to the remotely locatedwireless communications receiver, and thus to the central server.